Wis. Admin. Code NR § 811.79
If the storage or primary pumping facilities cannot provide a minimum static pressure of 35 psi throughout the distribution system at street elevation, it shall be necessary to create a boosted pressure zone to serve those portions of the system. The use of pressure boosting systems on individual service lines shall be limited to a maximum of 10 individual systems in any given service area. The minimum static water pressure at street elevation shall be 20 psi in order for individual pressure boosting systems to be installed. Individual pressure boosting systems shall be owned and maintained by the water system owner. Booster station design shall be in accordance with this subchapter.
Wis. Admin. Code Department of Natural Resources § NR 811.79